A US Apache helicopter, shot down by Iran on June 9 and prompting retaliatory bombings from the United States, was reportedly involved in a clandestine ship-to-ship oil transfer operation designed to maintain the flow of Gulf energy exports.

This intricate operation used aerial and water drones, along with helicopters, to guide convoys to awaiting tankers, according to four sources, including a former U.S. official with direct knowledge of the incident. Satellite imagery reviewed by Reuters revealed six pairs of tanker ships clustered in a small area off Oman’s port of Sohar on the day the Apache was downed.

While Reuters could not independently confirm the Apache’s specific role, a U.S. defense official, responding to inquiries, stated that no Central Command forces are participating in an offshore ship-to-ship oil transfer operation. Both crew members of the downed helicopter were rescued by a drone boat, U.S. officials confirmed.

The operation, situated on the periphery of the Strait of Hormuz, employs a shuttling technique long utilized by Iran to circumvent sanctions.

Eleven individuals familiar with the initiative identified two primary locations for these oil transfers: one off the coast of Fujairah in the United Arab Emirates and another near Oman’s port of Sohar. Commencing in early May, the transfers have involved at least 92 ships, according to shipping data and satellite imagery reviewed by Reuters.

As recently as June 11, satellite images showed 17 pairs of vessels conducting simultaneous oil transfers at these two sites. The full scope of these transfers, their operational mechanics, and the Apache’s involvement had not been previously reported. The White House directed questions to Centcom, while the Iranian government did not respond to requests for comment regarding the transfer operation.

These two transfer points, located in the Gulf of Oman near the Strait of Hormuz exit, lie close to boundaries established by the Persian Gulf Strait Authority, a new Iranian entity tasked with managing the Strait of Hormuz.

Vessels failing to comply with Iran’s directives face the risk of drone and missile attacks from the Islamic Revolutionary Guard Corps. The Fujairah port itself has endured repeated Iranian fire during the period this US-led operation has been active. Just last weekend, the British maritime risk management group Vanguard reported an “unknown projectile” striking a tanker off the coast of Oman.

Vanguard stated the crew was safe, and while the impact caused some cargo leakage, no environmental damage occurred. It did not specify if the tanker was part of a ship-to-ship transfer.

Iran’s response to the US-Israeli war effectively closed the Strait of Hormuz, a critical waterway through which approximately one-fifth of global oil consumption typically passes. This closure triggered the largest global energy supply disruption in history, fueling inflation worldwide.

The ship-to-ship transfers, despite being risky and inefficient, appear to be part of the Trump administration’s efforts to help restore normal oil flows from the Gulf.

President Donald Trump announced this week that the Strait of Hormuz would reopen Friday under a framework peace deal with Iran, though details remain vague. Reuters could not ascertain whether the announced deal had impacted the oil transfers.

A Reuters investigation published on May 20 previously detailed Iran’s own system for guiding ships through the opposite side of the Strait, involving island checkpoints, diplomatic agreements, and sometimes fees.

The American transfer operations are under the full control of the U.S. military, according to eight sources, including a private security contractor involved in the transfers. Tankers must navigate to a designated meeting point before reaching the strait, then stagger their departures, maintaining distances of 3,000 to 4,000 meters, as confirmed by one source and satellite imagery.

Their transponders are deactivated, and lights dimmed, according to four sources. A series of waypoints enables the U.S. military to monitor the progress of the designated tankers, with one source noting, “the Americans are obviously watching you all the time.”

Upon passing through the strait, just beyond a zone Iran has delineated as under its control, the tankers pull alongside recipient vessels, identified as Very Large Crude Carriers (VLCCs), to commence the oil transfers.

These transfers typically take between 24 and 40 hours to complete. The empty tankers then shuttle back through the strait, while the newly loaded VLCCs continue their onward journey. This ship-to-ship operation is made possible by a select few shippers willing to navigate their vessels through the strait to deliver oil to waiting tankers, despite the Iranian blockade.

However, the operation carries inherent risks. Noam Raydan, a senior fellow at the Washington Institute specializing in maritime risk, who reviewed Reuters’ findings, cautioned, “You just don’t know when Iran might decide to start using drones or even gunboats in order to prevent even those ships from transiting the strait.”

The ship-to-ship technique has been employed by Iran for years to bypass sanctions, as it effectively masks the origin of the oil. Iranians typically operate one pair of ships at a time, both to avoid detection and because of their relatively small pre-war export volumes.

In contrast, the U.S.-led operation, involving mass transfers, offers Gulf producers enhanced protection against Iranian retaliatory attacks, enabling them to move crude, condensate, and petroleum products to international buyers.

Reuters reviewed over a dozen satellite images taken between May 2 and June 11, depicting ship-to-ship transfers involving state-owned Gulf tanker fleets and internationally operated vessels receiving the oil. LSEG and Kpler shipping data reviewed by Reuters also showed repeated rendezvous between tankers operating in the area during the same period.

Based on this imagery, Reuters calculated that at least 90 million barrels of crude oil and petroleum products may have moved through this offshore network since early May. These volumes, based on the tankers’ carrying capacities, remain small compared to the pre-war average of approximately 20 million barrels that transited the strait daily.

Michael Froman, president of the Council on Foreign Relations, observed in a note Friday, “As the old rules weaken, it’s ironic that the United States is now taking a page out of the playbook of China, Russia, North Korea, and even Iran, whose so-called ‘dark fleets’ pioneered these techniques precisely to evade U.S. and UN sanctions.”

He was referring to the practice of sending ships through the strait without transponders, a point Donald Trump mentioned in comments on June 10 following the Apache’s downing. Six sources with direct knowledge of the operation confirmed that the U.S. has supported participating vessels through a combination of aerial surveillance, compliance screening, and monitoring, rather than direct naval escort. Reuters found no indication of direct involvement by US military personnel in the transfers themselves.

The receiving end of the operation is predominantly handled by international tanker operators, according to a review of shipping records. Greece-based Dynacom Tankers Management, for instance, has alluded to its efforts to find creative ways to ship oil through the strait since the war began on February 28.

George Procopiou, Dynacom’s founder, told a Capital Link shipping conference in Athens on June 1, “Freedom of navigation is essential and nobody can impose tolls or any other burden. We are here to serve, and Greece has the tradition of breaking blockades since antiquity. I don’t want to go into more details, but I believe the hints are enough to understand what I mean.”

Dynacom did not immediately respond to a request for comment on the U.S. operation.

However, another maritime source indicated that this new system introduces its own set of risks for the industry. “There is a paucity of reliable data,” the maritime security source stated.

With transponders used to communicate ship locations switched off, “companies are not reporting through the usual reporting centers.” This situation heightens the risk of collisions between vessels, which often travel at night with their lights off at speeds that hinder easy maneuvering, according to multiple shipping industry officials.

Four sources familiar with the arrangements confirmed that operators seeking access to the system must undergo a compliance review process before being allocated transit windows. This process involves submitting information to the U.S. Navy’s Naval Cooperation and Guidance for Shipping office in Bahrain.

Two preliminary compliance documents reviewed by Reuters mandated operators to provide complete geospatial tracking histories, full beneficial ownership disclosure, cargo documentation, and a willingness to permit cargo testing. If approved, participating vessels are assigned transit windows and maintain contact with the US military office in Bahrain throughout their voyage.

Emirati exports constitute a substantial portion of the US transfer operation, according to shipping records reviewed by Reuters. Six sources confirmed that the UAE’s state-owned national oil company ADNOC has been among the most active participants in the US-led transfers.

The Kuwait Oil Tanker Company has also been active. Approximately 2.3 million barrels of crude were siphoned from one of its ships off the coast of Sohar on June 6, one of the busiest days for the transfers, according to TankerTrackers.com data.

The receiving ship, Sea Ruby, was spotted five days later off India’s southwest coast, bound for China, where the cargo was expected to be discharged. The UAE government, ADNOC, and the Kuwait Oil Tanker Company did not respond to requests for comment. “I don’t see a permanent solution in all of this,” said Raydan. “This is a temporary solution amid exceptional times.”